Colorful radiation refrigeration flexible film as well as preparation method and application thereof

Abstract

The invention discloses a colored radiation refrigeration flexible film and a preparation method and application thereof, and belongs to the technical field of cooling films. The colored radiation refrigeration flexible thin film is composed of a white thin film layer, a protruding layer and a colored thin film layer which are sequentially arranged. The cross section of the protruding layer is one or more of a semicircle shape, a semi-oval shape and a wing shape, the height of the protruding layer is 5-500 micrometers, and the distance between every two adjacent protrusions is 5-500 micrometers. The colored radiation refrigeration flexible thin film structure is asymmetrically designed, one side of the thin film structure is of a porous structure doped with nano silicon dioxide, the porous structure is filled with colored pigment with a high reflection effect on near-infrared light, and solar energy can be selectively reflected to generate specific colors; the other surface is a layered porous three-phase composite material with less silicon dioxide, and one side of the contact surface is subjected to dispensing or mold molding or a part with a processed shape is directly added to form a structure with a fixed shape, so that the solar reflection can be improved to the maximum extent.

Description

Technical Field

[0001] The present invention relates to the technical field of cooling films, and more specifically to a color radiation cooling flexible film and a preparation method and application thereof. Background Art

[0002] In the hot summer, cooling measures are essential at all scales, including but not limited to residential and industrial areas. In the past 10 to 20 years, as the global greenhouse effect intensifies, the highest summer temperature records around the world have been constantly refreshed. While people are working hard to adopt various cooling solutions, they are also working hard to reduce energy consumption and carbon dioxide emissions.

[0003] Passive daytime radiative cooling is a promising strategy to achieve surface cooling of objects without any external energy consumption. Building energy simulations show that if colored radiative cooling flexible films are deployed in China, more than 600 MJ / m2 can be saved throughout the summer. 2 Passive daytime radiation cooling is achieved by using one or more devices and materials to make materials that can effectively reflect solar energy and radiate heat to the cold outside space through an atmospheric transparent window without the need for additional energy input. Ideal passive daytime radiation cooling materials usually have a solar reflectivity close to unity, which makes most materials appear white or mirror-like. This appearance limitation greatly inhibits their widespread practical application. Summary of the invention

[0004] In view of the above problems, the present invention provides a color radiation cooling flexible film and its preparation method and application. The preparation is simple and scalable, aiming to improve the universality of its use. The film structure is asymmetrically designed. One side is a porous structure doped with nano-silicon dioxide, filled with color pigments (up to 89%) with high reflective effect on near-infrared light, which can selectively reflect solar energy to produce specific colors; the other side is a layered porous three-phase composite material with less silicon dioxide, and the contact surface is glued or molded or directly added with processed parts to form a fixed shape structure, which can maximize solar reflection. Both parts of the color radiation cooling flexible film show extremely high mid-infrared reflectivity and emissivity, achieving obvious radiation heat loss, so the color film has a significant effect on reducing temperature during the day. In addition, because the reflectivity and emissivity of the two-layer structure of the film are inconsistent, the color film achieves different radiation cooling effects.

[0005] The first object of the present invention is to provide a color radiation cooling flexible film, which is composed of a white film layer, a protrusion layer, and a color film layer arranged in sequence;

[0006] The cross section of the protrusion layer is one or more of a semicircular shape, a semi-elliptical shape, and a wing shape. The height of the protrusion layer is 5-500 μm, and the distance between two adjacent protrusions is 5-500 μm.

[0007] Preferably, the color film layer has a thickness of 5-500 μm.

[0008] Preferably, the thickness of the white film layer is 20-500 μm.

[0009] Preferably, the total thickness of the color radiation cooling flexible film is in the range of 25-1000 μm.

[0010] Preferably, the white film layer is obtained by coating a white slurry and then drying it;

[0011] The white slurry is prepared according to the following steps:

[0012] Using alcohol solution as solvent and silane coupling agent as modifier, inorganic nanoparticles are modified by hot pressing to obtain modified nanoparticles;

[0013] The modified nanoparticles, polyacrylonitrile and polyvinyl pyrrolidone are dispersed in an organic solvent, and a white slurry is prepared by a phase separation method.

[0014] Preferably, the color film layer is obtained by pouring a color slurry and then drying it;

[0015] The color paste is prepared according to the following steps:

[0016] The modified nanoparticles, inorganic pigments, polyacrylonitrile and polyvinyl pyrrolidone are dispersed in an organic solvent, and a color slurry is prepared by a phase separation method.

[0017] Preferably, the inorganic pigment is one or more of titanium nickel yellow, cerium sulfide red, and Prussian blue.

[0018] The second object of the present invention is to provide a method for preparing the above-mentioned color radiation cooling flexible film, which is characterized by following the steps:

[0019] Step 1, coating the white slurry on a flat plate, immersing it in water for a coagulation bath, and then drying and coagulating to form a white film layer;

[0020] Step 2, a protrusion layer is provided on the white film layer, and the protrusion layer is obtained by immersing the film layer in water for a coagulation bath and then drying and coagulating the film layer;

[0021] Step 3: pouring colored slurry on the white film layer containing the protrusion layer, and after the colored slurry covers the protrusion layer, performing a water coagulation bath, separating and drying to obtain a colored radiant cooling flexible film.

[0022] The third object of the present invention is to provide the use of the above-mentioned colored radiation cooling flexible film in the preparation of cooling materials.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The colored radiative cooling flexible film of the present invention adopts a multilayer structure mode, and the colored side is a layered porous structure, which is mainly composed of a large amount of filled nanoparticles (such as silica particles) and highly reflective inorganic pigments, absorbs visible wavelengths to present the desired color, and has a higher near-infrared wavelength (NIR) reflectivity.

[0025] The white side on the back is a porous three-phase composite structure that combines the advantages of nanoparticles (such as silica) and a hierarchical porous structure (the colored side). It can enhance the backscattering of sunlight transmitted by the colored side, while adding microstructures that increase solar reflectivity and reduce unnecessary solar absorption.

[0026] In the yellow radiative cooling flexible film prepared by the present invention, the NIR reflectivity of the yellow side is 89%, while the wide solar reflectivity of the back side is 90%. Due to the phonon-enhanced Frohlich resonance of nanoparticles (such as silica microspheres), both sides have a high emissivity (98%), and both sides have different cooling effects. Therefore, by combining the two methods to achieve the cooling function, the application scenarios of radiative cooling films can be made more extensive and more effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a hot pressing experimental device for preparing modified nano-silicon dioxide particles of the present invention;

[0028] Figure 2 It is a schematic structural diagram of a colored radiation cooling flexible film prepared by adding a hemispherical structure on a white film layer prepared by the present invention through a dispensing machine;

[0029] Figure 3 It is a schematic structural diagram of a colored radiation cooling flexible film prepared by dispensing a semicircular cross-section long strip structure formed by dispensing glue on a white film layer prepared by the present invention;

[0030] Figure 4 This is a test result diagram of Example 1 of the present invention, showing the temperature variation over time in the yellow radiation cooling flexible film, the yellow cooling film without the white layer, and the experimental box sealed with a PE film.

[0031] Figure numerals: 1-upper hot pressing plate, 2-lower hot pressing plate, 3-hot pressing material, 4-mold, 5-color film layer, 6-white film layer, 7-hemispherical protrusion structure, 8-color film layer, 9-white film layer, 10-long strip structure with semicircular cross section. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] In this embodiment, a colorful radiative cooling flexible film is firstly provided, which has excellent radiative cooling performance and is suitable for the surfaces of objects such as buildings and vehicles that require radiative cooling.

[0035] The embodiment of the present invention also provides a color radiation cooling flexible film material and a manufacturing method thereof, including: preparation of modified nanomaterials, preparation of a white film layer and a surface protrusion layer structure, and preparation of a color radiation cooling flexible film color layer.

[0036] The modified nanomaterial preparation method comprises the following steps:

[0037] 10 g of silica nanoparticles were dispersed in 200 g of ethanol to obtain a mixture; 4 g of (methyltrimethoxysilane) MTMS and 1.5 g of deionized water were added to the mixture, and Figure 1 The mixture was stirred at 90° C. for 9 h in a hot press; washed with ethanol three times after centrifugation; and dried at 60° C. to obtain MTMS-modified silica nanoparticles. The silica used in this example is silica nanoparticles with a particle size of 900 nm.

[0038] The method for preparing the white film layer and the surface protrusion layer structure comprises the following steps:

[0039] 8 g of modified silica particles, 2.4 g of polyacrylonitrile (PAN), and 0.44 g of polyvinyl pyrrolidone (PVP) were uniformly dispersed in N, N-dimethylformamide (DMF) and reacted at 30°C for 1 h to obtain a white slurry, which was coated on a glass surface and immersed in 25°C distilled water for a coagulation bath for 6 h, and then dried and coagulated to obtain a white film layer with a thickness of 200 μm;

[0040] The white film layer is dotted with glue to form a hemispherical protrusion layer with a semicircular cross-section. The protrusion diameter is 80 μm, and the average spacing between two adjacent protrusions is 50 μm. Figure 2 As shown in , the same coagulation bath is then dried to obtain a white film layer containing a protrusion layer. In this embodiment, the protrusion layer can also be prepared by sputtering, or a hemispherical shape with a semi-elliptical cross-section can be prepared and then laid on the surface.

[0041] The preparation method of the color layer of the color radiation cooling flexible film comprises the following steps: dispersing 0.4g titanium chrome yellow pigment and 4g modified silica nanoparticles in DMF; uniformly dissolving 0.22g PVP and 0.6g PAN in the mixture, reacting at 30°C for 1h to form a color slurry; casting the color slurry on the above-mentioned white base film, requiring to cover the hemispherical protrusion layer on the white layer, and subjecting the entire adhesive layer to a distilled water coagulation bath for 6h; after the film is separated, it is dried at 60°C, and the thickness is controlled to be 100μm, so as to obtain the desired yellow radiation cooling flexible film, and the total thickness of the film is controlled to be 300μm.

[0042] The colorful radiation cooling flexible film prepared in the embodiment of the present invention has a structure as follows Figure 2 As shown, the NIR reflectivity of the yellow pigment is 72%. The yellow film color is measured facing the light source, and the color side of the yellow radiation cooling flexible film can achieve a cooling effect of 8.9°C lower than the temperature in the experimental box. It can be seen that the yellow radiation cooling flexible film prepared in this way has a higher reflectivity in the solar radiation band, effectively blocks the solar radiation input, and has an excellent radiation cooling effect.

[0043] Example 2

[0044] In this embodiment, a colorful radiative cooling flexible film is firstly provided, which has excellent radiative cooling performance and is suitable for the surfaces of objects such as buildings and vehicles that require radiative cooling.

[0045] The embodiment of the present invention also provides a method for manufacturing a color radiation cooling flexible film material, including: preparing a nano-modified material, preparing a white layer and a surface protrusion structure, and preparing a color radiation cooling flexible film.

[0046] The preparation method is the same as that of Example 1, except that the protrusion layer is a long strip structure with a semicircular cross section, and the white film layer is processed by a dispensing machine to have a long strip structure with a semicircular cross section, and the cross-sectional diameter is 80 μm. Figure 3 shown.

[0047] The yellow radiative cooling flexible film prepared in the embodiment of the present invention was tested and the usage was as follows: Figure 3 As shown, the yellow film color side is facing the light source for testing. The colored side of the yellow radiation cooling flexible film can achieve a cooling effect that is 8.7°C lower than the temperature in the experimental box. It can be seen that the yellow radiation cooling flexible film prepared in this way achieves a higher reflectivity in the solar radiation band, effectively blocks the input of solar radiation, and has an excellent radiation cooling effect.

[0048] Example 3

[0049] In this embodiment, a colorful radiative cooling flexible film is firstly provided, which has excellent radiative cooling performance and is suitable for the surfaces of objects such as buildings and vehicles that require radiative cooling.

[0050] The embodiment of the present invention also provides a method for manufacturing a color radiation cooling flexible film material, including: preparing a nano-modified material, preparing a white layer and a surface protrusion structure, and preparing a color radiation cooling flexible film.

[0051] The modified nanomaterial preparation method comprises the following steps:

[0052] 10 g of silica nanoparticles were dispersed in 200 g of ethanol to obtain a mixture; 4 g of MTMS and 1.5 g of deionized water were added to the mixture and stirred at 90° C. for 9 h; after centrifugation, the mixture was washed with ethanol three times; and after drying at 60° C., MTMS-modified silica nanoparticles were obtained. The silica used in this example was prepared by mixing silica nanoparticles with a particle size of 900 nm and silica nanowires with a diameter of 300 nm in a mass ratio of 1:1.

[0053] The preparation of the white layer and the surface protrusion structure and the preparation of the color radiative cooling flexible film are the same as those in Example 1, and the overall thickness of the color film is 300 μm.

[0054] The colorful radiation cooling flexible film prepared in the embodiment of the present invention has a structure as follows Figure 2 As shown, it was tested that the film of this embodiment can achieve a cooling effect of 7.5°C lower than the temperature in the experimental box. It can be seen that the yellow radiative cooling flexible film prepared in this way achieves a higher reflectivity in the solar radiation band, effectively blocks the input of solar radiation, and has an excellent radiative cooling effect.

[0055] Example 4

[0056] In this embodiment, a colorful radiative cooling flexible film is firstly provided, which has excellent radiative cooling performance and is suitable for the surfaces of objects such as buildings and vehicles that require radiative cooling.

[0057] The embodiment of the present invention also provides a method for manufacturing a color radiation cooling flexible film material, including: preparing a nano-modified material, preparing a white layer and a surface protrusion structure, and preparing a color radiation cooling flexible film.

[0058] The preparation method is the same as that of Example 1, except that:

[0059] The thickness of the white film layer is 500 μm;

[0060] The protrusion layer is a long strip structure with a wing-shaped cross section. The long strip structure with a wing-shaped cross section is processed on the white film layer by a dispensing machine. The average spacing between two adjacent protrusions is 500μm. The wing shape is a flat convex wing shape, the upper surface is a curved surface, and the lower surface is a horizontal surface. The chord length is 700μm, the maximum thickness is 500μm, and the maximum thickness is located at 1 / 5 of the horizontal direction.

[0061] The inorganic pigment used in the color film layer is cerium red sulfide, the thickness of the color film layer is 500 μm, and the total thickness of the color radiation cooling flexible film is 1000 μm.

[0062] Example 5

[0063] In this embodiment, a colorful radiative cooling flexible film is firstly provided, which has excellent radiative cooling performance and is suitable for the surfaces of objects such as buildings and vehicles that require radiative cooling.

[0064] The embodiment of the present invention also provides a method for manufacturing a color radiation cooling flexible film material, including: preparing a nano-modified material, preparing a white layer and a surface protrusion structure, and preparing a color radiation cooling flexible film.

[0065] The preparation method is the same as that in Example 1, except that:

[0066] The thickness of the white film layer is 20 μm; the nanoparticles are a mixed material obtained by mixing silicon nitride nanosheets with a sheet diameter of 10 μm and aluminum phosphate nanoparticles with a particle diameter of 700 nm in a mass ratio of 1:1.

[0067] The silane coupling agent is vinyl trisilane.

[0068] The protrusion layer is a long strip structure with a semicircular cross-section, and the white film layer is processed by a dispensing machine to have a long strip structure with a semi-elliptical cross-section. The height of the semi-elliptical cross-section is 5μm, the cross-section diameter is 20μm, and the average spacing between two adjacent protrusions is 5μm.

[0069] The inorganic pigment used in the color film layer is Prussian blue, the thickness of the color film layer is 5 μm, and the total thickness of the color radiation cooling flexible film is 25 μm.

[0070] Example 6

[0071] In this embodiment, a colorful radiative cooling flexible film is firstly provided, which has excellent radiative cooling performance and is suitable for the surfaces of objects such as buildings and vehicles that require radiative cooling.

[0072] The embodiment of the present invention also provides a method for manufacturing a color radiation cooling flexible film material, including: preparing a nano-modified material, preparing a white layer and a surface protrusion structure, and preparing a color radiation cooling flexible film.

[0073] The preparation method is the same as that in Example 1, except that:

[0074] The nanoparticles are a mixed material obtained by mixing titanium dioxide nanoparticles with a particle size of 100 nm and aluminum oxide nanoparticles with a particle size of 300 nm in a mass ratio of 1:1, and the silane coupling agent is a silane coupling agent obtained by mixing vinyl triethoxy silane and vinyl trimethoxy silane in a mass ratio of 1:1.

[0075] The thickness of the white film layer is 300 μm;

[0076] The protrusion layer is a long strip structure A with a semicircular cross-section and a long strip structure B with a semi-elliptical cross-section, which are processed on the white film layer by a dispensing machine. The diameter of the semicircle is 100μm, the height of the semi-elliptical cross-section is 50μm, and the cross-sectional diameter is 160μm. The long strip structure A with a semicircular cross-section and the long strip structure B with a semi-elliptical cross-section are arranged alternately, and the spacing between two adjacent protrusions is 300μm.

[0077] The inorganic pigments used in the color film layer are titanium nickel yellow and Prussian blue in equal amounts. The thickness of the color film layer is 100 μm, and the total thickness of the color radiation cooling flexible film is 400 μm.

[0078] Comparative Example 1

[0079] In this comparative example, a single color film layer is proposed for comparison based on the thickening of the color layer in the above-mentioned color radiant cooling flexible film.

[0080] The method for preparing the color thin film layer in the comparative example of the present invention is as follows:

[0081] The preparation method of the nano-modified material is the same as that in Example 1.

[0082] The method for preparing a colored film comprises the following steps: dispersing 0.8 g of titanium chrome yellow pigment and 8 g of modified silica nanoparticles in DMF to obtain a mixture; uniformly dissolving 0.44 g of PVP and 1.2 g of PAN in the mixture; coating the colored slurry on a glass sheet and subjecting the entirety to a distilled water coagulation bath for 6 hours; and drying the film at 60° C. after separation to obtain a desired single yellow film, wherein the total thickness of the film is controlled at 300 μm.

[0083] By comparing Example 1 and Example 2, it is found that the measured temperatures of Example 1 and Example 2 are lower than the single yellow film prepared in Comparative Example 1. The temperature of the single yellow film is measured to be 5.6°C lower than the ambient temperature. The radiative cooling effect of the colored radiative cooling flexible film prepared by the present invention is significantly improved.

[0084] Comparative Example 2

[0085] In this comparative example, a color refrigeration film without a protrusion layer is proposed based on the above-mentioned color radiant refrigeration flexible film for comparison.

[0086] The method for preparing the colored refrigeration film without a protrusion layer in the comparative example of the present invention is as follows:

[0087] The preparation method of the nano-modified material is the same as that in Example 1.

[0088] The preparation method of the white film layer and the color film layer is the same as that of Example 1. The thickness of the white film layer is 200 μm, and the total thickness of the color refrigeration film without the protrusion layer is 300 μm.

[0089] By comparing Example 1 and Comparative Example 2, it is found that the measured temperature of Comparative Example 2 is 6.3° C. lower than the ambient temperature. Compared with Example 1, the radiative cooling effect of the colorful radiative cooling flexible film prepared by the present invention is significantly improved.

[0090] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0091] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A color radiation cooling flexible film, characterized in that: The color radiation cooling flexible film is composed of a white film layer, a protrusion layer, and a color film layer arranged in sequence; The cross section of the protrusion layer is one or more of a semicircular shape, a semi-elliptical shape, and a wing shape. The height of the protrusion layer is 5-500 μm, and the distance between two adjacent protrusions is 5-500 μm.

2. The color radiative cooling flexible film according to claim 1, characterized in that: The thickness of the color film layer is 5-500 μm.

3. The color radiative cooling flexible film according to claim 1, characterized in that: The thickness of the white film layer is 20-500 μm.

4. The color radiative cooling flexible film according to claim 1, characterized in that: The total thickness of the color radiation cooling flexible film ranges from 25 to 1000 μm.

5. The color radiative cooling flexible film according to claim 1, characterized in that: The white film layer is obtained by coating the white slurry and drying it; The white slurry is prepared according to the following steps: Using alcohol solution as solvent and silane coupling agent as modifier, inorganic nanoparticles are modified by hot pressing to obtain modified nanoparticles; The modified nanoparticles, polyacrylonitrile and polyvinyl pyrrolidone are dispersed in an organic solvent, and a white slurry is prepared by a phase separation method.

6. The color radiative cooling flexible film according to claim 5, characterized in that: The color film layer is obtained by pouring the color slurry and drying it; The color paste is prepared according to the following steps: The modified nanoparticles, inorganic pigments, polyacrylonitrile and polyvinyl pyrrolidone are dispersed in an organic solvent, and a color slurry is prepared by a phase separation method.

7. The color radiative cooling flexible film according to claim 6, characterized in that: The inorganic pigment is one or more of titanium nickel yellow, cerium sulfide red and Prussian blue.

8. A method for preparing the color radiation cooling flexible film according to claim 6, characterized in that: Follow these steps: Step 1, coating the white slurry on a flat plate, immersing it in water for a coagulation bath, and then drying and coagulating to form a white film layer; Step 2, a protrusion layer is provided on the white film layer, and the protrusion layer is obtained by immersing the film layer in water for a coagulation bath and then drying and coagulating the film layer; Step 3: pouring colored slurry on the white film layer containing the protrusion layer, and after the colored slurry covers the protrusion layer, performing a water coagulation bath, separating and drying to obtain a colored radiant cooling flexible film.

9. Use of the colorful radiation cooling flexible film according to any one of claims 1 to 7 in preparing cooling materials.

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